This chapter provides a detailed analysis of efficiency wage models--an important class of labor market models of relatively recent vintage--and discusses their implications for the comparable worth debate. The authors argue that, in such models, the existence of sizable industry wage differentials unrelated to job attributes such as education or work experience may provide a justification for a comparable worth standard and that, to the extent that it enhances worker efficiency, adoption of comparable worth may have smaller effects on employment than have usually been contemplated. The authors add that the greatest impact of comparable worth might be in high-wage industries, where relatively few women are employed. If so, comparable worth might increase wage inequality among women even as it reduces wage disparities between men and women.